146 KANSAS CITY REVIEW OF SCIENCE. 
the first cost of a motor, as compared with a steam enghie, the saving in attend- 
ance and fuel, the convenience and cleanHness, and in some cases a saving in insur- 
ance by reason of there being no fire risks attendant upon its use. At just what 
point steam becomes preferable, however, is a question depending considerably 
upon water-rates, but to some extent on other circumstances, leaving it largely a 
question of judgment. As with elevators, there are difficulties involved in their 
supply that unless carefully guarded make water motors anything but a desirable 
source of revenue. How often is the argument advanced : " Why, I only use 
water for a quarter of an inch jet," showing how little people who use motors 
or elevators or fountains realize the quantity of water they consume. This class 
of consumers may be placed on one footing, to-wit : a class who, in spite of the 
fact that they are supplied with water for much less than any other, feel that they 
are imposed upon, and cannot be made to think otherwise. 
Though not as large as for elevator supply, water motors require liberal open- 
ings in the mains, and frequently the fault of having too small supply pipes, is 
sought to be remedied by openings in the water mains much larger than needful. 
A table prepared by an engineer who had given the matter study, or by some 
motor manufacturer, showing the size of taps, or openings, for the proper sup- 
ply of motors, with the various jets, under different pressures, would be of general 
use to water-works people. In order to use water to the best advantage, the full 
pressure in the main, so far as practicable, should be had at the jet, but in order to 
accomplish this it is not necessary to use as large taps as are ordinarily demanded, 
but to provide supply pipes of sufficient capacity to deliver the water to the point 
of discharge with the least possible friction. Lately this theory has been put in 
practice to some extent by us, and the result has shown that in this manner we 
are able to supply motors through smaller taps than before, and with as satisfac- 
tory results. 
It is a general practice throughout the country to make annual or monthly 
rates for water motors, and from my observations I believe I can safely venture 
the assertion that in three-quarters of the cases the rates charged will not equal 
fifty per cent of the lowest meter rates in force in these places. 
I have made some estimates myself for water motors, basing rates upon the 
number' of hours it was claimed the motors would be in use, and afterward sup- 
plied the same motors by meter measurement, and in every case found that at 
least twice as much water was used as had been estimated. Although estimates 
were carefully made upon what was beheved to be a reliable basis, these repeated 
similar results have lead me to the conclusion, that the only way to supply motors 
is to make it an object to the users of them to be economical. In other words, I 
believe the way to supply water motors is upon an estimate that they will run 
twenty-four hours per day and 365 days per year, or more properly still, supply 
them only by meter measurement. At all events this is henceforth my policy, or 
in other words, " On this rock I stand," believing it the only equitable way out of 
this difficulty. 
That class of motors, or water-engines, operated by water-pressure in close: 
